An endoscope is a medical device that is used to observe within a subject. Due to miniaturization and increase in performance of solid-state image pickup devices (CCD sensor, CMOS sensor, and the like), endoscopes (namely, electronic endoscopes) that have been mounted with a solid-state image pickup device at the tip of an inserting portion are widely available.
As such an electronic endoscope, there are devices that are for observing inside a thin lumen such as a blood vessel, a bile duct, and a ureter. These endoscopes require complicated operations during insertion into the lumens. Thus, for example, there is a case where a guidewire is inserted in advance into a subject using fluoroscopy, and the endoscope is inserted along such guidewire. Note that, the guidewire is used to guide a medical appliance such as a catheter or a stent, other than the endoscope, to a target region within the subject.